has part has part characteristic of inheres in has modifier natural killer cell Abnormal natural killer cell morphology Abnormal total natural killer cell count Abnormal increase or decrease of total natural killer (NK) cells, commonly characterized as CD3-CD19- and CD16+ or CD56+ lymphocytes, in the blood, per microlitre, or altered NK cell phenotype, compared to a reference range for a given sex and age-group, measured ex vivo. Abnormal NK cell count Abnormal number of natural killer cells Abnormality of natural killer cell count UMLS:C4021036 In human peripheral blood, five NK cell subpopulations can be defined on the basis of the relative expression of the markers CD16 and CD56: (1) CD56bright CD16- (50-70% of CD56bright), (2) CD56bright CD16dim (30-50% of CD56bright), (3) CD56dim CD16-, (4) CD56dim CD16bright, and (5) CD56- CD16bright. In healthy individuals, populations (3) and (5) are numerically in the minority. amount abnormal